انگشت‎نگاری ژنتیکی بخشی از ژرم‎پلاسم خربزه ایران با استفاده از نشانگر‎های ریز‎ماهواره

آگاهی از میزان تنوع ژنتیکی بر اساس نشانگر‎های مولکولی روشی سریع است که نقش مهمی در برنامه‎های اصلاحی دارد. در این بررسی تنوع ژنتیکی 40 توده محلی خربزه از مناطق شرقی و مرکزی ایران با استفاده از 15 جفت آغازگر ریز‎ماهواره مورد ارزیابی قرار گرفت که 13 جفت از آغازگر‎های مورد استفاده، قادر به تکثیر مکان‎های ژنی ریز‎ماهواره شدند. تمام مکان‎های ژنی به جز آغازگر cmct44، چند شکل بودند، در مجموع تعداد 25 آلل با میانگین 1/93 آلل به ازای هر جایگاه ژنی ریز‎ماهواره، مشاهده گردید. بالا‎ترین میزان مکان‎های چند شکلی (84/62 درصد) متعلق به توده kc-357009 بود. میزان بالای مکان‎های چند شکلی، تایید‎کننده کارآیی نشانگر‎های مولکولی ssr در آنالیز ژنتیکی توده‎های بومی مورد بررسی است. میانگین محتوای اطلاعات چند شکلی و هتروزیگوتی مورد انتظار به ترتیب 0/24 و 0/23 به‎دست‎آمد. مقادیر بالای هموزیگوتی مشاهده شده با میانگین 0/84 نشان‎دهنده تنوع پایین درون توده‎های مورد بررسی است که دلیلی بر میزان پایین دگر‎گشنی بین توده‎ها و میزان بالای خویش‎آمیزی است. در بررسی ساختار ژنتیکی جمعیت‎ها، توده‎های مورد بررسی در دو گروه (زیر‎جمعیت) قرار گرفتند. نتایج حاصل از تجزیه ساختار جمعیت بر‎اساس روش بیزین و خوشه‎بندی upgma نشان داد که طبقه‎بندی ژنوتیپ‎های مورد مطالعه مستقل از منشاء جغرافیایی‎شان می‎باشد. با توجه به مقادیر حاصل از پارامتر‎های فوق از بین آغازگرهای مورد مطالعه، مکان‎های ژنی cmcca145، cmga172 و cmct134b جهت تجزیه و تحلیل مجموعه‎های ژرم پلاسم خربزه در تحقیقات آتی توصیه می‎شود.

genetic fingerprinting of a part of iranian melon germplasm using microsatellite markers

introduction: awareness of the extent of genetic diversity based on molecular markers is a rapid method that plays an important role in breeding programs. cucumis melo l. is the scientific name for a melon that belongs to the cucurbitaceae family (kirkbride, 1993). this plant is a popular garden crop in warm and temperate climates across the globe, and iran ranks fourth in the world in terms of output (faostat, 2019). although several studies were conducted on the genetic structure of iranian melons using various molecular markers including rapd molecular markers (feizian, 2004), issr (maleki et al., 2018) and ssr microsatellite markers (moayedi nejad et al., 2010; raghami et al., 2014) in recent years, due to the history of planting and the presence of huge genetic resources of melon, which makes iran as one of the main centers of diversity of this crop in the world, research is inadequate.materials and methods: forty native melon stands used in this research were prepared from the melon germplasm of iran gene bank. 4-5 leaves from each plant at the two- to three-leaf stage were collected and kept in a freezer at -80°c until dna extraction. their genomic dna was extracted using the zandbio plant kit. the markers used in this research were selected based on previous studies that were suggested by different researchers. gradient pcr vapo protect thermocycler was used for polymerase chain reaction. pcr products were electrophoresed on 1.8% agarose gel in 1x tbe buffer and at 85 v for one hour. observation and photographing of the gel was done with the help of uv-2100 geldoc device. bands were scored as zero (not seeing a band) and one (observing a band). evaluation of cluster analysis and genetic parameters such as observed heterozygosity, expected heterozygosity and number of effective alleles were obtained through ntsys 2.1 and popgene 1.32 software. to estimate the number of subpopulations (k) and distinguish pure and mixed genotypes, it was done using structure software version 2.3 and using the bayesian method (pritchard et al., 2000).results and discussion: all gene loci except cmct44 primer were polymorphic. a total of 25 alleles with an average of 1.93 alleles per microsatellite gene locus were observed. the highest amount of polymorphic sites (84.62%) belonged to kc-357009 genotype.. the high amount of polymorphic sites confirms the effectiveness of ssr molecular markers in the genetic analysis of the investigated indigenous populations. the average content of polymorphism and expected heterozygosity information was obtained as 0.24 and 0.23, respectively. the observed high homozygosity values with an average of 0.84 indicate the low diversity within the investigated populations, which is a proof of the low level of variation between the populations and the high level of inbreeding. in the investigation of the genetic structure of the populations, the investigated populations were divided into two groups (sub-populations). the results of population structure analysis based on bayesian method and upgma clustering showed that the classification of studied genotypes is independent of their geographical origin.conclusion: according to the values obtained from the above parameters, among the studied primers, gene locations cmcca145, cmga172 and cmct134b are recommended for the analysis of melon germplasm collections in future research.the results of this study can be used in hybridization programs. crossing between the figures that have the least similarity will lead to the best results in achieving hybrids or achieving maximum separation in the generations after f1. although genetic distance is not the only effective factor in identifying suitable parents for hybrid production and factors such as compatibility and genetic distance based on morphological traits should also be considered.